A novel life cycle assessment methodology for transitioning from nZEB to ZEB. Case-study

• Published in: Journal of Building Engineering 2024-11, Vol.97, p.110868, Article 110868
• Main Authors: Palomar-Torres, Amalia, Rey-Hernández, Javier M., Rey-Hernández, Alberto, Rey-Martínez, Francisco J.
• Format: Article
• Language: English
• Subjects: Climate change mitigation; GWP; nZEB; Operational carbon emissions; Renewable energy; Sustainable buildings
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2024.110868

This study analyzes the CO2 equivalent emissions of a LEED-certified nearly Zero Energy Building (nZEB) using a simplified Life Cycle Assessment (LCA) methodology, aligned with EN 15978. Focusing on the building's energy performance across its life cycle, the study demonstrates that in 2022, 95 % of the energy used for heating came from renewable sources, which decreases to 86 % by 2050 due to milder winters. However, the need for cooling increases by 9 % over the same period due to hotter summers. By 2050 and 2080, if the EU transitions to renewable electricity, the operational Global Warming Potential (GWP) could approach zero. The study highlights that embodied emissions (69 %) outweigh operational emissions (31 %) in 2022, emphasizing the need to reduce embodied GWP through material reuse and recycling. Notably, concrete and aluminum were found to contribute the most to embodied emissions. The research also shows that nZEBs can exceed the EU's 2030 energy targets, with renewable energy contributing 67 % of the building's total consumption. As climate change favors nZEB performance, the operational emissions will trend towards zero, but embodied emissions will become increasingly significant. To achieve the EU's zero-emission goals, it is crucial to prioritize reducing embodied GWP in future nZEBs. This study underscores the importance of nZEBs in mitigating climate change impacts, offering a pathway toward sustainable construction and energy efficiency. •Advanced LCA methodology evaluates nZEB's life cycle emissions.•Circular economy approach essential for reducing GWP at nZEB.•LCA method reveals nZEBs' high sustainability and low GWP.•Short-therm nZEB goal: to reduce embedded GWP.•Study underscores nZEBs' role in EU's energy transition.